New install- Can't change anything, can't be administrator

I'm completely new to Windows 7, and I just started it up on my brand new PC today. Not a good start- I seem to have somehow become locked out of the ability to be an administrator, which also means that I can't change anything at all.

I'm guessing it was caused by two things that I did, in attempt to make Windows 7 less irritating.

1) I put that slider about notifying me when programs are changed down to 'never notify me'. It seemed like a harmless thing to turn off, but it seems this may be connected to 'UAC' and may have caused the problem? Only thing is, now I can't change it at all.

2) I used 'netplwiz' to uncheck 'users must use a password to login to this computer', because I have no need or wish to have to type a password every time windows starts. When asked which account to login to automatically, I selected the user account I made when I installed windows. This, at the time I selected it, was in the groups 'homeusers AND administrators', but now it's only in 'homeUsers'. And I now can't turn the 'users must use a password to login to this computer' thing- well I can check or uncheck the box but when I log in, it still automatically logs me in to the same account.

I seemingly can't change anything at all or install any programs.